trade-in vs holding

trade-in and holding both are nouns.

Word	Noun	Adjective	Verb	Adverb
trade-in	Yes	No	No	No
holding	Yes	No	No	No

As nouns, holding is a hypernym of trade-in; that is, holding is a word with a broader meaning than trade-in:

trade-in: an item of property that is given in part payment for a new one
holding: something owned; any tangible or intangible possession that is owned by someone

Other hypernyms of trade-in include belongings, property.

trade-in (noun)	holding (noun)
an item of property that is given in part payment for a new one	the act of retaining something
	something owned; any tangible or intangible possession that is owned by someone